How long ago did you rebuild these ponds? If recently, it could be that the pond just hasn't had enough time to cycle. I would try to determine why one pond has a higher organic load than the other that is, as I read it, only a few feet away. A series of partial water changes may help, but again the problem should dissipate on its own. Periodically my own pond will develop this phenomena, but it is usually will return to normal within 24 - 48 hours.